Forest bathing enhances human natural killer activity and expression of anti-cancer proteins.

Q. Li*, K. Morimoto, A. Nakadai, H. Inagaki, M. Katsumata, T. Shimizu, Y. Hirata, K. Hirata, H. Suzuki, Y. Miyazaki, T. Kagawa, Y. Koyama, T. Ohira, N. Takayama, A. M. Krensky, T. Kawada

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

150 Scopus citations

Abstract

In order to explore the effect of forest bathing on human immune function, we investigated natural killer (NK) activity; the number of NK cells, and perforin, granzymes and granulysin-expression in peripheral blood lymphocytes (PBL) during a visit to forest fields. Twelve healthy male subjects, age 37-55 years, were selected with informed consent from three large companies in Tokyo, Japan. The subjects experienced a three-day/two-night trip in three different forest fields. On the first day, subjects walked for two hours in the afternoon in a forest field; and on the second day, they walked for two hours in the morning and afternoon, respectively, in two different forest fields. Blood was sampled on the second and third days, and NK activity; proportions of NK, T cells, granulysin, perforin, and granzymes A/B-expressing cells in PBL were measured. Similar measurements were made before the trip on a normal working day as the control. Almost all of the subjects (11/12) showed higher NK activity after the trip (about 50 percent increased) compared with before. There are significant differences both before and after the trip and between days 1 and 2 in NK activity. The forest bathing trip also significantly increased the numbers of NK, perforin, granulysin, and granzymes A/B-expressing cells. Taken together, these findings indicate that a forest bathing trip can increase NK activity, and that this effect at least partially mediated by increasing the number of NK cells and by the induction of intracellular anti-cancer proteins.

Original languageEnglish (US)
Pages (from-to)3-8
Number of pages6
JournalInternational journal of immunopathology and pharmacology
Volume20
Issue number2 Suppl 2
DOIs
StatePublished - Jan 1 2007

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Pharmacology

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